<div class="widget widget_search">
    <form class="navbar-form" action="/search.html" method="get">
        <div class="input-group">
            <input type="text" name="keyword" class="form-control"  size="35" placeholder="请输入关键字" maxlength="15" autocomplete="off">
            <span class="input-group-btn">
                  <button class="btn btn-default btn-search" type="submit">搜索</button>
             </span>
        </div>
    </form>
</div>